Error installing DTW

I am trying to install DTW on a server that was recently upgraded from 2005A to 2007A, SP01, PL08. I have un-installed the previous version of DTW that was working fine prior to the upgrade. When I try to install DTW now, I get the error message : Error 1317. An error occurred while attempting to create the directory c:\program files\SAP\Data Transfer Workbench.

I am not even installing to that folder - I am trying to install on d:\program files\sap\data transfer workbench. The location above is where the old version was installed.

I am logged in as the administrator, and have verified the folder permissions. I have create the folder manually, and run the install both with and without the folder in existence. Nothing that I do seems to make a difference. Any suggestions would be much appreciated.